Fun in the morning time entertains service staff (9)
I believe the answer is:
amusement
'fun' is the definition.
(amusement is fun or enjoyment)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for amusement that I've seen before include "(State of) finding something funny" , "Pleasure, diversion" , "Light-hearted pastime" , "set up through arcade?" , "Fun" .)